Position control servomotor



Feb. 20, 1951 w. D. TEAGUE, JR 2, POSITION CONTROL smvouowox Filed Dec. 26; 1947 2 Sheets-Sheet 1 INVE NTOR MHL TER 0. 75/7505, JR.

ATTORN EY w. D. T EAGUE, JR

POSITION CONTROL SERVOMQTOR Feb. 20, 19 51 2 Sheets-Sheet 2 Filed Dec. 26, 1947 1 1 l-Xw .NAAAAIWAA?MU I v l QVENTOR ll/HLTER D. TEHEUE, JR. I

ATTORNEY Patented Feb. 20, 1951 umrsn sums PATENT orrics 2,542,187 POSITION CONTROL SERVOMOTOR Walter D. Tune, Jr., Alpine, N. 3., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware 7 Application December 28, 1347, Serial No. 793,967

, 2 Claims. 1

The invention hereof relates to position control servos, and particularly to devices of this character which are adapted for fluid operation.

An object of the invention is to provide a servo or positioning control unit which shall maintain substantially constant pressure for operating a valve or other device irrespective of altitude variations.

Another object is to minimize acceleration efi'ects as by providing maximum pressure of many times the opposing force of the device to be operated. I

Another object is to provide novel sealing means for pressure regulating means to insure sea-level pressure at the side of the means opposit to its regulating pressure side, whereby the pressure regulating means will control to the same absolute pressure at all times.

Another object is to provide a device with rapid action so that, if the system is upset for any reason, lag is minimized in reestablishing equilibrium.

Another object is to provide a device of the above-indicated character which is simple and durable in construction, economical to manufacture, and effective in its operation.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

In the drawing:

Figure l is a view on an enlarged scale, taken substantially along the line I--I of Figure 2, of a structure constricted in accordance with the invention.

Figure 2 is a view on a reduced scale taken substantially along the line 22 of Fig. l; and

Figure 3 is a view taken partially in side elevation and partially along the line 3-3 of Fig. 2.

Referring to the drawing:

The device comprises a housing I included, in the normal operative upright position indicated, a body I2 having internally screw threaded upper and lower end portions or lengths I4 and II, respectively, a constricted mid section I8 delining a bellows-receiving fluid-pressure regulating chamber or space 20, an inlet 22, Figure 2, to the space 20, an upper partition or wall 24 having a through aperture 28, and an outlet 28 from a servo chamber 30.

A housing portion 32, of inverted substantially cup-shape constituting a closure for the end I4 and therewith defining a regulating spring compartment 34, is threaded into the end I4, sealed as by a gasket 36, and adapted for the screw threaded reception of a cap 38 which compresses a gasket 40 against the end wall 42 of the cup portion 32 and has a raised hollow nut portion 44. Th wall 42 has an interiorly threaded depressed portion 46 for the reception of a cup point socket screw 48 held by a nut 50.

A sleeve-like portion 52 of the housing I0, threaded into the body I2 against a gasket 34, cooperates with the body to define the chamber 30, and is provided with an inner shoulder 56.

A bottom cover 58 for the sleeve 52 is of shallow substantially cup-shape forming a spring base 60 having an edge margin 62 under the shoulder 88 and an apertured bearing portion 64. A ring nut 68 is threaded into the sleeve 52 below the margin 82.

A fluid-responsive positioning means or bellows 88, of inverted substantially cup-shape and disposed in the chamber 30, has an open-end perimeter 10 sealed, as by a gasket 12, between the shoulder 56 and the margin 62. A disc 14, constituting the closed end of the cup bellows 68, has a top-side upright perimetral flang 13 and an integral depending positioning shaft 18 axially slidably journaled in the bearing 84.

A separate valve plate or partition 80, below the chamber 30 held against a shoulder 82 of the mid section I 8, as by a ring nut 83, and positioned angularly, as by a pin or pins 85, Figure 3, has, in this instance, an annular top guide 84, and underside or bottom abutment means 86 within the flange 16, and is provided with a valve seat inset 88 having a regulating orifice 90 through the plate from the space 20 to the chamber 30. A spring 92, around the shaft 18 in the bellows 88 is maintained under compression between the base 60 of the cover 58 and the disc 14 against the abutment 88.

An upright regulating bellows 94, of substantially cup-shape in the space 20, includes an open end rim 36 held around the aperture 26 in the wall 24, as by a ring nut 91, and has a closed end 98 guided in the top guide means 84 and carrying a valve element I00 for controlling the regulating orifice 30. The valve element I00, in this case, constitutes a substantially V-section oi the closed end 38 constituted as the valve at its lower side and as a socket at its upper side.

An annular element I02, of substantially Y- section extending through the aperture 28, includes an upper spring seat I04 in, and near the bottom of, the compartment 34, and a depending l8 leg I08 in the regulatin bellows 84 having a lower end I08 in, and complemental to, the upper side socket of the V-section valve I00.

An upper spring seat I 58, of substantially cupshape, in the compartment 34, surrounds the screw 48 and has an apertured bottom seat II2 for a single-ball bearing II4 which is seated at the top by the lower or cup end of the screw 48. A spring H6 is disposed under compression between the seats I04 and I I0.

As better seen in Figure 3, an outlet duct II8 from the chamber 30 to the outlet 28 has portions I20 and I22 in series in the plate 80 and the The tube I38 is connected to apparatus in which pressure is to be regulated, and the tube I39 communicates with a region of low pressure such as a pump inlet or an overboard outlet.

In operation, the pressure regulating bellows spring I I8 is adjusted so that the regulating bellows 94 will raise the valve I00 off its seat 88 at a predetermined liquid discharge pressure at the inlet 22, in this instance of about 425 p. s. i. gage. If the liquid pressure rises too high, the

.regulating bellows 84 further opens the regulating orifice 90 to admit more high pressure liquid to the servo chamber 30. Since the outlet bleed orifice I28 is considerably smaller than the regulating orifice 90, pressure builds up in the servo chamber 30, compressing or contracting the positioning bellows 88 and its spring 92, to extend the shaft I8 from its retracted positions shown. which action is transmitted to apparatus for effecting a decrease in pressure of the fluid being controlled so that this pressure drops to a preset value.

When the system is satisfied, and in equilibrium, the regulating bellows 80 maintains the valve I00 in position partially throttling the regulating orifice 80.

In case the discharge pressure drops below the preset value, the regulating bellows 94 moves the valve I08 to further close the orifice 90 and cuts down the fiow of high pressure liquid into the servo chamber or space 30.

As the liquid drains through the fixed bleed orifice I28 to the low pressure outlet 28, the pressure in the servo chamber 30 is decreased and allows the positioning spring 92 to extend the bellows 88 to retract the shaft I8. This action serves to increase the fluid pressure to its preset value. 'As soon as equilibrium is again established, the regulating bellows 94 causes the valve I00 to resume a position partially throttling the regulating orifice 90, in which the action is so rapid that little lag occurs inreestablishing equilibrium when the system is upset for any reason.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

1. In combination in a position-control servo, a housing comprising, in one position, upper and 4 lower body end portions section defining a space, an inlet to the space, an apertured upper wall of said space and an outlet from a chamber; an inverted closure cup threaded and sealed in said upper end and therewith defining a compartment, a cap threaded and sealed over the cup, a sleeve threaded and sealed in said lower end to form said chamber and having an inner shoulder, a bottom cover for the sleeve forming a spring base having an edge margin under the shoulder and a bearing. and a ring nut below said margin; an inverted cup positioning bellows in said chamber having an open-end.

perimeter sealed between the shoulder and the margin and a closed end disc having a top upright perimetral flange and an integral depending shaft journaled through said bearing; a plate below said chamber having a top guide, a bottom abutment within said flange, and an inset having a regulating orifice through the plate; a ring nut'holding the plate against the mid section; a spring around the shaft in compression between the base and the disc against the abutment, a regulating bellows of upright cup-shape in said space including an open-end rim and having a closed end in the guide carrying a valve for said regulating orifice, a ring nut holding the rim against said wall, an element of Y-section through the aperture of said wall having a top spring seat in said compartment and a depending leg in said regulating bellows against said valve, a screw through the closed end of the closure cup, a cup spring seat surrounding the screw, a singleball bearing between the screw and the cup seat, a spring in compression between the seats, said body and plate forming a duct from the chamber to the outlet, and an inset plug in the body having a bleed orifice in the duct of smaller diameter than the first orifice.

2. In combination in a position-control servo, a housing comprising, in one position, upper and lower body end portions and a mid section de' fining a space, an inlet to the space, an apertured upper wall of said space and an orifice from the space to a chamber; means in said upper end and defining with said upper end a compartment, means sealed in said lower end to form said chamber and a spring base and bearing, a positioning bellows in said chamber having a depending shaft journaled through said bearing, a spring around the shaft in compression between the base and the bellows, a regulating bellows in said space and carrying a valve for regulatin said orifice, an element through the aperture of said wall having a spring seat in said compartment and a depending leg in said regulatin bellows against said valve, a second spring seat in said compartment, a spring in compression between the seats, and a bleed orifice from the chamber to an outlet of smaller diameter than the first mentioned orifice.

WALTER D. TEAGUE, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS and a constricted mid 

